The unintentional leakage of urine, known as urinary incontinence, afflicts about 13 million people in the United States. One type of urinary incontinence, referred to as stress urinary incontinence (SUI), is the unintentional urine leakage during times of abdominal stress, such as that which may occur during coughing, laughing, or sneezing. One cause of SUI is inadequate anatomical support of the urethra which allows the urethra to move out of the retropubic space and rotate into the vagina. This condition is known as “hypermobility of the urethra” or simply “hypermobility.” SUI may also result from insufficient closing pressure of the urethra which prevents the urethra from fully collapsing and sealing. This condition is known as intrinsic sphincter deficiency (ISD).
SUI patients are generally categorized into three types: Type I, Type II, and Type III, depending upon a patient's particular symptoms. A Type I SUI patient is classified as a patient that has involuntary urine leakage without hypermobility. Type I SUI is the mildest and least common type of UI, being present in only about 13% of SUI patients.
Type II SUI refers to patients with urethral hypermobility. Type II is the most common type of SUI, afflicting about 37% of SUI patients. Type II SUI is most commonly found in women and is often a result of child birth which can weaken the anatomical structure that supports the urethra.
Type III SUI refers to patients with ISD. Type III SUI is the second most common type of SUI and is estimated as being the solitary cause of incontinence in about 33% of SUI patients. As mentioned above, unlike Type II SUI, which is due to a lack of anatomical support and associated hypermobility, Type III SUI is a result of a defect in the urethra itself, in which the urethra fails to fully close. Type III SUI is often caused by scarring of the urethra which prevents the urethra from properly collapsing and sealing. It has recently been suggested however, that every woman with stress incontinence has some component of Type III (ISD).
A variety of devices have been developed for the treatment of SUI. For example, urethral slings are commonly used to treat the hypermobility associated with Type II SUI and artificial sphincters have been used to treat ISD. To treat SUI, a urethral sling is typically implanted below the urethra to provide support under the urethra and prevent unwanted movement of the urethra down into the vagina. A variety of different slings and associated implantation methods have been developed. Early pubovaginal slings were designed for placement toward the posterior urethra at its junction with the bladder neck to raise the urethra and/or bladder neck from a descended position.
More recent slings have been implanted at midurethra under no tension. These midurethral slings are generally not intended to raise the urethra but to provide a “backboard” for the urethra to prevent the unwanted urethral movement associated with hypermobility. A typical midurethral sling comprises a tape that is implanted using a transvaginal approach in which opposite ends of the tape are arranged on opposite sides of the urethra so that the tape loops under the urethra to form a sling. The tape is typically implanted using needles that attach to the tape of the sling so that the tape's ends can be inserted into the body and exit out of the body at a desired exit site. Excess tape extending out of the body can be removed and the remainder of the tape left in the body to act as a sling. The sling is held in place by friction.
More specifically, a tension-free vaginal tape (TVT) has been developed that may be implanted using a transvaginal approach in which the tape is implanted below the urethra and exits the abdominal wall. Another device, known as transobturator tape (TOT), has been developed and a method for implanting TOT developed by Delome, in which the TOT is placed between two obturator foramen to create a hammock to support the urethra. The TOT may be inserted around the ischiopubic ramus in a horizontal plane through the two obturator foramina. More recently, TVT-O tape has been developed for implantation using a method of penetrating the obturator foramen from the vaginal incision towards the thigh fold.
These urethra slings have proven successful in treating up to 90% of Type II patients, but have a long term effectiveness of only about 74% in Type III (ISD) or mixed Type II and Type III cases. The failure of these slings may be due to dislocation of the sling. For example the sling may become dislocated from its desired midurethral position and move back toward the bladder. In addition, even if a sling is properly positioned, thereby curing the hypermobility, the patient may also suffer from ISD which the sling may not adequately address.
Presently, there are few good alternatives for assisting those patients for whom a urethral sling fails to provide a satisfactory continence level. One option is to install an additional urethral sling. But adding an additional sling results in a complicated support system that entails another invasive surgery.
Another approach is to try to provide additional closing pressure to the urethra to treat possible ISD. As previously mentioned, artificial sphincters have been used to increase urethral closing pressure. In addition to requiring invasive surgery, these devices tend to be large and complicated and designed to treat patients with a high level of ISD. Many patients are resistant to having two surgeries and two incontinence devices. It would be desirable to have a single device that could address both hypermobility and ISD and be implanted in a single surgery.
Another technique to increase closing pressure of the urethra is to inject a bulking agent into the tissue surrounding the urethra to increase support about the urethra. While this technique has shown to be useful in improving continence levels of patients, its effect is only temporary due to the absorption of the bulking agent by the body over time. Accordingly, a patient will often require repeated injections in order to maintain a desired level of continence. In addition, the injection of the bulking agent directly into the tissue is not easily undone once injected and can lead to severe complications in the event too much bulking agent is injected. Side effects can be especially serious when more permanent bulking materials are used. Direct tissue injections also do not provide a structure for tissue ingrowth about the injection site and therefore often result in encapsulation and the development of scar tissue. The injections may also lead to fluid collections around the injections which can lead to infection. Further, once injected, the bulking agent is not easily removed. This may lead to serious complications if too much bulking agent is injected which compresses the urethra to the point that the patient is unable to urinate. In those cases, the patient must then rely on self-catheterization to empty the bladder. The injections may also raise the urethra to an undesired height.
Another option is to adjust the implanted sling itself. For example, many surgeons attempt to improve continence by pulling on the ends of the sling to increase the sling tension. This seldom has a positive effect and often results in further complications such as de novo urge incontinence. For example, tightening the sling tends to raise the urethra as the sling is pulled taught which can move the urethra to a position higher than desired. In addition, attempting to tighten the sling often dislocates the sling from its desired mid-urethra location to a position back toward the bladder. This can lead to “urge” incontinence in which a patient has symptoms of overactive bladder, thereby leaving the patient worse off after surgery than before. In addition, tightening the sling does not provide a uniform closing pressure about the bottom and sides of the urethra as most of the force will be concentrated at the bottom of the urethra when the sling is pulled tight. In order to apply sufficient closing pressure to the urethra the sling must therefore be pulled very tight so that the upward force to the bottom of the urethra is sufficient to force the urethra to close, effectively strangling/occluding the urethra. Furthermore, as discussed above, for best performance the sling should not be under tension.
A few slings have been developed that provide for postoperative adjustment of some type, but the adjustment of such slings is typically complicated, difficult, and invasive. These slings also tend to be susceptible to dislocation from a desired midurethral position during adjustment. The prior art slings also tend to be promote scar tissue development. Therefore, the prior art adjustable slings typically require adjustment soon after surgery before scar tissue develops and prevents the fine tuning of the sling. These slings are also prone to raising the urethra to an undesired height during adjustment.
U.S. Pat. No. 6,117,067 to Gil-Vernet teaches the implantation of a urethral sling beneath the urethra that is adjustable to raise the urethra. The sling is connected by threads to an expandable container implanted remotely from the urethra, such as in the adipose tissue. The sling may be tightened by injecting bulking agent into the remote container to lift the strings and thereby lift the sling and raise the urethra. While fit for its intended purpose, that procedure is complicated, requiring insertion of both the sling and the container in different sites. Furthermore, as discussed above, tightening the tension of the sling tends to raise the urethra to an undesired height. Furthermore, tightening the sling does not provide uniform pressure about the bottom and sides of the urethra or provide means to accurately manage such bottom and side forces, as most of the force will be applied beneath the urethra. Furthermore, studies have shown that it is desirable to leave the sling non-tensioned for correcting hypermobility.
U.S. Pat. No. 7,083,637 to Tannhauser discloses a urethral sling, referred to as a tape, that may be adjusted post-operatively to change support under the urethra. Tannhauser teaches implanting a sling using a retropubic approach in which curved needles are used to pass one end of the tape into the body via the vagina at one side of the urethra and over the pubis and through the abdominal wall and pass a second end of the tape on the other side of the urethra in the same manner to form a sling around the urethra. Mechanical adjusting means may be provided in the form of sutures located on the tape to adjust the length of one or both sides of the tape in near proximity to the urethra to adjust the effective length of the supporting arms of the tape. The sutures remain accessible through the incision in the vagina for a period of time after implantation, such as a few days to adjust the length of the supporting arms of the tape used to support the urethra.
Tannhauser also teaches attaching an expandable container to the tape and implanting the tape so that the container is between the tape and the urethra. The sling may be adjusted postoperatively by injecting bulking agent directly into the expandable container or to a port located in close proximity to the container. To inject the bulking agent the surgeon must make an injection into the vagina. Not only can this be uncomfortable for the patient but it is difficult to accomplish and raises the possibility of inadvertently puncturing the bladder or urethra. According to Tannhauser, upon injection of bulking agent into the expandable container, the tissue between the mesh and the urethra will expand resulting in a simple vertical lifting due to expansion and a vertical lifting due to stretching the outside of the mesh.
While fit for its intended purpose, Tannhauser has several drawbacks. First, the location of the expandable container and injection port within the vagina make it difficult to locate and inject the bulking agent, likely requiring a vaginal incision to re-expose the container or injection port. The difficulty in locating the expandable chamber or injection port make injecting the bulking agent into the container a complicated and risky process that will require repeated vaginal incisions and vaginal needle punctures to inject the bulking agent. The positioning of the injection port in the vagina will likely be poorly received by a sexually active patient and may lead to dyspareunia.
Tannhauser also does not provide for normal tissue ingrowth between the urethra and the container resulting in the development of scar tissue. Tannhauser teaches attaching the expandable container to the tape so that the chamber is exposed to the tissue between the urethra and the tape. This arrangement will promote the development of scar tissue, which lacks the resilience of ingrowth tissue, and once the capsule of scar tissue has developed around the container, it will prevent expansion of the container. The Tannhauser device must therefore be adjusted within a few days after surgery before the development of scar tissue which would prevent the expansion of the container. Scar tissue will also prevent adjustment of the container to provide additional support as the patient ages. Adjustment of the Tannhauser device also requires that the patient be in a lithotomic or supine position. However, testing patient incontinence requires the patient to stand. Thus, the patient will be forced to alternate between the standing and supine position during the adjustment process.
Expansion of the Tannhauser arrangement will also apply most of the force to the bottom of the urethra and without providing significant lateral support. Nor will the device provide lateral support that is adjustable independently of the lower support to provide a more uniform closing pressure. Thus, in order to provide sufficient urethral closing pressure, the container of Tannhauser would need to be inflated to a large size in order to provide sufficiently large force to the bottom of the urethra. This is likely to cause dislocation of the sling from the desired mid-urethral location to a position near the bladder which can lead to urge incontinence. In addition, the expansion of the container may position the urethra to a position higher than desired or significantly increase the tension on the sling. Furthermore, Tannhauser will not provide effective treatment for male incontinence, as the device would likely slide posteriorly off of the bulbous urethra and allow pressure to be applied directly to the anterior rectal wall, providing no beneficiary urethral compression or relocation.
What is needed is a urethral sling that effectively addresses both hypermobility and ISD. What is also needed is an incontinence device that is postsurgically adjustable to a patient's needs. What is also needed is a tension free urethral sling that can be adjusted to provide increased urethra pressure without causing dislocation of the sling. What is also needed is a tension free urethral sling that can be adjusted to increase urethral closing pressure without significantly increasing the tension on the sling. What is also needed is a urethral sling that is easily adjustable after surgery to provide increased support to the urethra without significantly changing the position (height) of the urethra. What is also needed is a urethral sling that promotes tissue ingrowth and minimizes infection risks. What is also needed is a urethral sling that is adjustable over long periods such as years. What is needed is a urethral sling that is easily adjustable after surgery without incisions or invasive surgery. What is needed is a sling that can be adjusted while the patient is in the standing position. What is also needed is a device that does not interfere with the sex life of the patient. What is also needed is a device that is suited to treat both male and female incontinence.